Field theory is a psychological theory which examines patterns of interaction between the individual and the total field, or environment. The concept was developed by Kurt Lewin, a Gestalt psychologist, in the 1940s.

Field theory holds that behavior must be derived from a totality of coexisting facts. These coexisting facts make up a "dynamic field", which means that the state of any part of the field depends on every other part of it. Behavior depends on the present field rather than on the past or the future.

Kurt Lewin (1890-1947) was a famous, charismatic psychologist who is now viewed as the father of social psychology. Born in Germany, Lewin emigrated to the USA as a result of World War II. Lewin viewed the social environment as a dynamic field which impacted in an interactive way with human consciousness. Adjust elements of the social environment and particular types of psychological experience predictably ensue. In turn, the person's psychological state influences the social field or milieu. Lewin was well known for his terms "life space" and "field theory". He was perhaps even better known for practical use of his theories in studying group dynamics, solving social problems related to prejudice, and group therapy (t-groups). Lewin sought to not only describe group life, but to investigate the conditions and forces which bring about change or resist change in groups. In the field (or 'matrix') approach, Lewin believed that for change to take place, the total situation has to be taken into account. If only part of the situation is considered, a misrepresented picture is likely to develop.